1. Field of the Invention
The present invention relates to a steering device.
2. Description of the Related Art
Japanese Patent Application Publication No. 2009-90856 (JP 2009-90856 A) describes a steering device in which a steering shaft is inserted through a tubular steering column. In the steering column, an upper column and a lower column are assembled telescopically to enable position adjustment of a steering wheel in the axial direction. A clamp portion is mounted to the upper column. The clamp portion is supported by a second vehicle body-side bracket via a first vehicle body-side bracket so as to enable tilt position adjustment. A first through hole and a second through hole are formed in the clamp portion.
A tightening rod is inserted through the first through hole. A rotary shaft is inserted through the second through hole. An operation lever is mounted to one end of the tightening rod. A telescopic holding toothed cam having an eccentric tooth portion is rotatably coupled to the tightening rod. A rotation transfer portion that engages with the telescopic holding toothed cam is non-rotatably coupled to the rotary shaft. The rotary shaft and the operation lever are coupled to each other by a torsion coil spring.
When the operation lever is operated in the clamp direction, rotation of the operation lever is transferred to the rotary shaft via the torsion coil spring to rotate the rotary shaft. Consequently, an abutment piece of the rotation transfer portion contacts the upper side of the telescopic holding toothed cam while being elastically deformed, and thus the telescopic holding toothed cam is rotated so that the eccentric tooth portion of the telescopic holding toothed cam meshes with the outer periphery of the upper column. Consequently, the steering wheel is fixed in position.
Japanese Patent Application Publication No. 2010-254204 (JP 2010-254204 A) describes a steering device that includes an outer column and an inner column inserted through the outer column. A passage hole and a through hole are formed in the outer column. A rod-like member is inserted through the through hole. An adjustment lever is fixed to the base end portion of the rod-like member. An unlock lever is fitted with the rod-like member. A support shaft disposed in parallel with the rod-like member is inserted through the through hole. A telescopic lock eccentric cam is externally fitted with the middle portion of the support shaft. The distal end portion of the unlock lever faces a stepped receiving surface of the telescopic lock eccentric cam. The telescopic lock eccentric cam faces the upper surface of the inner column. When the adjustment lever is turned, the distal end portion of the unlock lever pushes the stepped receiving surface downward to turn the telescopic lock eccentric cam. Consequently, a telescopic lock depression/projection formed on the telescopic lock eccentric cam abuts against the upper surface of the inner column, which fixes the steering wheel in position.
In the steering device according to JP 2009-90856 A, an operation member such as the operation lever and the rotary shaft are coupled to each other by the torsion coil spring. Therefore, the urging force of the torsion coil spring acts on the operation lever, which may increase the operating force required to operate the operation lever. When the operating force is increased, the operability of the operation lever is reduced.
In the steering device according to JP 2010-254204 A, the clearance between the rod-like member and the support shaft must be kept at a predetermined distance in order to cause the distal end portion of the unlock lever, which is fitted with the rod-like member, and the stepped receiving surface of the telescopic lock eccentric cam, which is externally fitted with the support shaft, to face each other. Therefore, it is difficult to reduce the clearance between the rod-like member and the support shaft in the axial direction when the rod-like member and the support shaft are disposed side by side in the axial direction.
When an operation member such as the adjustment lever is disposed at a position away from the upper surface of the inner column, on the other hand, the rigidity of the steering device is reduced. Therefore, in the steering device according to JP 2010-254204 A, it is difficult to reduce the clearance between the rod-like member and the support shaft in the axial direction by disposing the rod-like member, which is provided with the adjustment lever, at a position away from the upper surface of the inner column.
Hence, there is a limitation on the reduction in clearance between the rod-like member and the support shaft in the axial direction of the inner column, which makes it difficult to downsize the steering device.